1. Field of Invention
The invention relates to an image processing method for digital image data and, in particular, to a method of separating graph data from text data in digital image data.
2. Related Art
In order to obtain a better printing quality or a sharper image effect, digital image data have to be analyzed. A common method is to separate the graph data and the text data in the digital image data. There are many ways to implement the separation of graphs and text in digital image data. Discussions of such techniques can be readily found in journals, academic theses, and patents. For example, the U.S. Pat. No. 5,379,130 (hereinafter as P130), U.S. Pat. No. 5,889,885 (hereinafter as P885), and U.S. Pat. No. 6,681,053 (hereinafter as P053) have disclosed related techniques.
The purpose of the patent P130 is to increase the printing quality of digital image data. This patent uses a 3×3 matrix to process the image. It further employs the edge enhancement and binary separation techniques to achieve the graph-text separation. The patent P885 utilizes a specific algorithm along with many operation thresholds to process images in order to obtain gray-level digital images of a better quality. The patent P053 emphasizes on the color presentation on LCD and PDP displays. It improves the horizontal resolution in the color matrix display. In this case, a matrix of a special size is used in company with table-looking operations and several operation thresholds.
Although the above-mentioned cases can separate graph and text data in a digital image with a reasonably good effect, it is not difficult to realize that they all involve complicated processes, many algorithms or table-looking. Therefore, they require a lot of operating time of the computer or the use of a processing chip with good performance. They thus suffer from the drawback of higher hardware costs.